1. Field of the Invention
The present invention relates to marking a target, and more particularly, to a handheld and/or weapon mounted device incorporating a quantum cascade laser for generating and impinging a thermal infrared beam upon a target to create a corresponding image in a thermal imager.
2. Description of Related Art
In contrast to image enhancement technology typically employed in “night vision,” “image intensifier” or “I2” devices, thermal imaging does not require any ambient light or supplemental infrared illumination to illuminate a target or to produce an image.
That is, in a thermal imaging device, thermal infrared radiation (typically ranging from approximately 2 microns to 30 microns in wavelength) is captured and converted into a visible image. Objects with temperatures above 0° Kelvin emit light energy (black body radiation), a portion of which is in the thermal infrared spectrum. Thus, all objects above 0° K are theoretically viewable by a thermal imaging device.
In one form of a thermal imaging device (a micro-bolometer array), the infrared radiation (photons at the infrared wavelength) are impacted against a phased array of infrared detector elements, which creates a temperature pattern, often called a thermogram. The thermogram is translated into electrical impulses which are sent to a signal processing unit which translates the information into a display, wherein the image typically appears as various colors, depending upon the intensity and wavelength of the received infrared emission.
Since certain molecules reacts to specific wavelengths in a predictable manner, the use of thermal infrared radiation (and sensing of such radiation) provides a means for identifying or determining the presence of a selected molecules.
There are several classes of lasers that are capable of emitting radiation in the appropriate wavelength spectrum. However, these devices require cooling to a low temperature.
None of these lasers provide for a handheld, portable configuration operable at ambient or room temperature. Therefore, the need exists for a handheld portable target marker which can impinge a thermal infrared beam (at a wavelength between approximately 2 microns and 30 microns) upon the target, thereby identifying the target when viewed with a thermal imaging system.